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Micro 5-2
Duke PA micro
Question | Answer |
---|---|
What are the four medically important clostridium infections? | C. perfringens, C. botulinum, C. tetani, C. difficile |
How does C. perfringens grow in vitro? | easily and rapidly |
Human disease caused by C. perfringens | ranges from mild gastroenteritis to severe myonecrosis |
5 serotypes of C. perfringens | A-E |
Which serotypes of C. perfringens responsible for most human disease? | type A |
virulence factors - C. perfringens | "lethal toxins" |
A-toxin | a lecithinase is produced in large quantities by type A strains of C. perfringens |
How does C. tetani grow in vitro? | difficult to grow in vitro |
What is characteristic of C. tetani on Gram stain? | terminal endospore |
Virulence factors - C. tetani | hemolysin, neurotoxin |
What does the neurotoxin in C. tetani do? | causes clinical expression of tetanus by blocking neurotransmitter release |
What is the etiologic agent of botulism? | C. botunlinum |
What groups is C. botulinium divided into? | I, II, III, IV - likely represents 4 different species |
What modulates disease cause by C. botulinum? | neurotoxin, types A-G (antigenically distinct) |
What are the three clinical presentations of botulism? | food borne, infant botulism, wound botulism |
What is the most common etiologic agent of antibiotic associated colitis (AAC)? | C. difficile |
C. difficile - normal flora | GI, in some |
What are the virulence factors of C. difficile? | toxin A: enterotoxin toxin B: cytotoxin |
What allows C. difficile to survive in hospital environment? | spore formation |
Where is C. difficile infection increasing? | in community outpatient populations - scary!! |
Is C. difficile an anaerobe or aerobe? | strict anaerobe |
What are the symptoms of AAC? | can be anything from relatively mild diarrhea to colectomy |
Lactobacillus - normal flora | mouth, GI, GU |
How is lactobacillus often recovered? | in large numbers of specimens (especially urine) as "contaminents" |
What are the clinical presentations of lactobacillus? | transient bacteremia, endocarditis, opportunistic septicemia |
How do mobiluncus and gardnerella appear on Gram stain? | Gram negative or Gram variable |
How are mobiluncus and gardnerella classified (gram negative or positive)? | gram positive |
Why are mobiluncus and gardnerella gram positive? | Gram positive cell wall, antibiotic susceptibility similar to Gram positive, lack endotoxin |
Where do mobiluncus and garnerella colonize in large numbers? | female genital tract |
What happens to number of mobiluncus and gardnerella in bacterial vaginitis? | increase dramatically |
Mobiluncus spp | M. curtisii, M. mulieris |
Propionibacterium | genus of small, gram positive rods |
How do propionibacterium appear on gram stain? | clumps or chains |
Is propionibacterium an aerobe or anaerobe? | anaerobes: some aerotolerant |
Propionibacterium - normal flora | skin, oropharynx, female genital tract |
Most medically important species of Propionibacterium | P. acnes |